Treatment as prevention

There's been a lot of talk about 'treatment as prevention' recently. A research trial called the HPTN 052 study showed that early HIV treatment – started at a CD4 count between 350 and 550 – reduced the risk of HIV transmission to an uninfected partner, by at least 96%. Almost all the study participants were heterosexual couples. The lead researcher, Professor Myron Cohen, said: "These are important results to give to a serodiscordant couple."

The debate on the infectiousness of patients taking HIV therapy was kick-started by the release of the Swiss statement in 2008, which said that – in certain circumstances – people taking successful antiretroviral therapy were not infectious to their sexual partners.

There's also been a lot of news on pre-exposure prophylaxis (PrEP) involves people who are HIV-negative taking anti-HIV drugs to prevent HIV infection. Two large studies have now shown that PrEP can cut the risk of HIV infection by up to 73% in heterosexual couples. The results of these two studies showed that  PrEP was equally effective at preventing infections in men and women. (An earlier study, FEM-PrEP, had suggested PrEP was unlikely to work in women.)

Research has suggested that gay men would find PrEP an acceptable prevention tool, with most men in the study saying it wouldn’t increase risk behaviour. However, another study suggests that gay men would need to feel confident that PrEP provided a high level of protection before they saw it as a replacement for condoms.

Plans to trial PrEP amongst gay men at 'high risk' of HIV infection are at an early stage in the UK. However, we don't yet know if PrEP will be an affordable prevention tool because of the cost of the drugs to the NHS. And, like all HIV treatment, the drugs used for PrEP can cause side-effects, which may put some people off using them.

Policy makers need to think how to use prevention technologies, such as HIV treatment, PrEP and microbicides, in an HIV prevention package. The strong message at the conference was that prevention methods are not in competition with each other. Using the right prevention technology to suit the needs of the individual is essential. The prevention effect of HIV treatment will be reduced if there continue to be large numbers of people who do not know that they are HIV positive.

And the issue of human rights will need to be carefully considered, with the needs of people with HIV at the centre of thinking and planning about the role of HIV treatment in prevention.

Every individual with HIV should decide for themselves when and how to start treatment," Eric Fleutelot, director of international programmes for Sidaction, a French HIV agency, said. "No one should be forced or coerced into treatment primarily for the benefit of the public health rather than the health or the wellbeing of the individual."

The World Health Organization will be organising a panel to look at the role of antiretrovirals for treatment and for prevention, over the next year, and to develop international guidance.